Design a transaction class for deposits/withdrawals

Design a **Transaction/Account** component that supports **deposits** and **withdrawals**. Assume you are building a backend library or service used by other parts of a financial application. ## Requirements - Maintain an account **balance**. - Support operations: - `deposit(amount)` - `withdraw(amount)` - `getBalance()` - Record a **transaction history** (at minimum: id, type, amount, timestamp, status). ## Constraints / edge cases to handle - Amount must be positive. - Prevent the balance from becoming negative (or clearly define overdraft rules). - Handle **concurrent requests** safely (e.g., two withdrawals at the same time). - Ensure operations are **atomic** and leave the account in a consistent state. - (Optional, if time) Support **idempotency** so retrying the same request doesn’t double-charge. Explain your design choices, data structures, and how you would test it.